People throw words around today without thought as to what they really mean. One web definition of "bionic" is "Having anatomical structures or physiological processes that are replaced or enhanced by electronic or mechanical components." (http://www.thefreedictionary.com/bionic)
One might think at first blush this would apply to a Microprocessor controlled knee. BUT the knee does NOT replace or enhance. It does not even come close to mimicking the human knee. They are fancy sticks with a usually single joint hinge. The only two Microprocessor four bar knees I know of - the DAW SLK and TruLife Power four bar - are four bar designs; and they suffer different but similar fates - of only swing microprocessor control - no stance, stumble recovery, stairs, slopes or other safety modes. BUT . . . you have to be a wearer of a knee to understand why the term "bionic" STILL does NOT apply.
A Microprocessor controlled knee - despite what everyone who DOES NOT wear one believes, does not interface with the human body in any way, nor does it augment the strengths thereof, nor can the wearer control it - once it has entered a certain mode. In a Microprocessor knee you cannot run, kick, squat, jump, lift from the knee - or safely lift at all, Indian sit (sitting with legs crossed) cross your legs, swivel on the ankle, stand tip toe, climb stairs - and the list goes on and on - of the really unwise, unsafe things to try to do - so forget any "mimic" of the human knee. No where near do they do that.
There are myoelectric hands - one is made by a company called "Bebionic", - and they are truly "bionic" in that a sensor is incorporated somewhere in the wearer's socket attached to receive impulse signals from the wearer at a point on their skin to operate the hand in some way by thought process. Even then it usually just to open and close the hand - forget about wrist control and etc. A Microprocessor controlled knee does nothing of the sort and in fact the knee operates by completely independent signals from force sensors - not the human body.
The microprocessor knees use force signals to "guess" at what to do next, - lock or unlock the knee - stiffen it for support - maybe too late in the process or worse stiffen it when you do not want it to; and use algorithms to vary the amount of resistance the knee has to a swing phase - and that is all. A major complain of the Rheo knee is that it just does that - stiffens when wearers do not want it to, and MAKES them stumble.
You know what - it does if not set up right and walked in right; and I mean the amputee's style of walking. I always find it amazing for someone who is NOT an Above Knee amputee (prostheticists and even yes - Below Knee [BK] amputees included) try to tell me how something works as an AK that I wear everyday. If you give it some thought it is a bit insulting.
I do not think people understand that for a new (or any) amputee to read misleading information having hopes and dreams they have not yet come to grips with as to the true reality of it is really cruel. Bebionic's (and any other manufacturer of any) myoelectric hand is - YES - bionic - the microprocessor controlled knee PLAINLY IS NOT. The hand works with muscle impulse sensors resting on pick up points on the human body for an interface signal so that by thought and muscle flex the hand will operate.
The knee has no such interface - and never can have any such interface. It would be nice to think "I'm stumbling and going to fall - kick the knee out to catch me" and it would do it. No such way - EVER - will any knee product on the market ever do that - it is NOT going to happen. Not even the Power Knee. It cannot - as such would require an interface into the human brain with a signal to some kind of intricate knee with motors in it to mimic the various muscles in the leg and ankle to pull up support of some kind just like a leg can AND coordinate with the other muscles needed to hop for balance and artful dance. Ain't gonna happen folks.
The Power Knee is the only thing on the market with motors, and it is really expensive and heavy, and power hungry, and just not practical. There exists a hard headed Pinocchio kind of mentality most of the general public has become just assuming things not in fact - and in fact that can never be and never was said to be.
A microprocessor controlled knee is a stick with a hinge that has a hydraulic valving system which tries to guess if you are walking or standing or if maybe it should kick some support in to hold the knee up. It uses a force sensor placed somewhere to send a signal or some have two sensors to send two signals. That is it.
I have seen others who are NOT amputees write articles on how great these knees are - and guess what - they have never worn one because they have two good legs and are guessing and dreaming - yet they are sure they are right. Maybe you have read one that brought you here thinking misleading things. It is like writing an article on what is like to be a woman because as a man you have read about it somewhere.
Think about the ludicrous nature of that. Even a drag queen or tranny is just guessing. There is a clear definition of bionic. It is a mechanical interface to a separate animate system. There is no interface to the knee - in fact there is no direct connection for good control - unless one is osseointegrated, and then that is only a direct connection to the bone. It carries no signals, and in fact with the current design of osseointegration and myoelectrics, can never carry a signal - absent extra wires, sensor leads and clumsiness.
People who do not wear these and think they have a clue how they truly operate, do not have a clue what they are talking about and are not qualified to make assessments or wrote about or on them because they are usually just excited journalists of some type who think what they write about exists. It does not exist - no more than the space ship Enterprise or the particle beam transporter of Star Trek fame exists. I am a prostheticist of AK things exclusively and work with a "two legged" prostheticist. He has a really hard head and I tell him all the time, you do not wear these things and you do not know, and you do not know how when an amputee sees or hears you say or do something that is flat out wrong - they just do not say anything; but your credibility just shrunk. I tell him nothing about this field is funny or deserves a joke. He seems to think it is an insult he cannot know or experience what I am talking about - and does not want to believe it that important - yet - would not really want to anyway. After all - it is still a "better you than me" mentality when it comes to loosing a limb.
The other day a guy came in who really could benefit from use of a Microprocessor controlled knee - and we had one in the shop he could try - Seattle's (TruLife) Fusion. It is a pneumatic - hydraulic hydrid similar the Endolite Adaptive. (Smart Adaptive now) It is a radial like the Rheo for hydraulics for stance - with a pneumatic cylinder for swing like the original IP knee was from Endolite / Blatchford. I told him that to put this knee on that guy working would be an instant sale - coming from walking on a blown Century 2000; - but the TruLife pneumatic four bar he ordered and had on his test setup leg the guy was NOT going to like because a hydraulic four bar walks completely differently than a pneumatic.
Pneumatic four bar knees have a mushy walk feel to them, while hydraulics have solid firm but in control measured swing. He scoffed - I told him I wear these - I have walked on both, and he is not going like it. The guy tried the new Seattle Pneumatic and hated it. Then my partner tried to set up the Microprocessor knee, and I had told him to do a dry run and be prepared. He did not. I told him how critical it was to set up the knee right - he did not listen. The way the amputee was accustomed to walking - he kept putting the knee into stumble recovery mode the way the guy was accustomed to walking - and my partner could not see what was happening. I stayed out of it. The amputee got sick of the bumbling around - and told him to just put his old leg back together and he was leaving after he got some rest from all this unnecessary workout.
Frankly the amputee was pissed, and I would have been too - and I did not say - I told you so - but he knew that is what I was thinking. I just looked at him - with his "15 years of experience." I told him I have 9 years of experience walking on lots of different knees.
These Microprocessor knees are nowhere near "bionic". It is just a hydraulic valve in a cylinder operated by a microprocessor from a force sensor located somewhere on the knee or leg trying to guess what you are doing - standing, walking, falling, going down a stair, going down a slope - trying to sit down - THAT IS IT. Remember and notice - there is no "climbing stair" mentioned, because it cannot be done without power assist to pull and lift like the muscle in a leg does. Only the Power Knee at this time does that - and it is bit clunky - and certainly quite NOISY with motors and gear sounds on how it does it.
The best leg on the market right now is the C-Leg for two simple reasons. 1 It is all hydraulic - even thought that is electromechanically hydraulic meaning if the power truely fails there is NO Hydraulics at all -. 2 The sensor is located in the pylon at the ankle area. This gives it fulcrum force information to use rapidly and continuously from that all important support and balance area - the ankle. Uh - Duh . . .
The only legs I have not walked on yet is the Fusion and the Plie 2.0. I will be waking on the Fusion this week; (2nd week of September 2010) and I will make a call to Freedom Innovations about a test walk in the Plie' 2.0. We will see what they say. Imagine someone writing a test drive type article without a test drive or even an engineering perspective on how the products differ. There are so many OTHER issues to truly mimicking a human knee - these microprocessor knees do not even reach 30% of that.
They are just a fancy stick with a - usually hydraulic (or hydraulic - pneumatic) hinge - PERIOD. Anyone telling you different - or writing something different is blowing smoke up your _____ - well you get the idea. Just like prostheticists - with two good legs - they are going to argue with an amputee about something they read in a book - when the amputee is telling them; they and the BOOKS are WRONG, and why - they walk it and wear it. Microprocessor controlled knees are NOT bionic - no way near close.
They do not interface with the muscle system at all, and they DO NOT mimic the human knee in it's complexity of swing and connection to the foot to dorsiflex the foot (lift the toe) or plantar flex (heel down ankle back foot flat) to the foot in control at all. This is an integral part of the walk cycle we take for granted. I do not understand why people who do not know and can never know, insist on putting themselves out there to make claims and promises to let someone down who is really an amputee and is depending on the written word being true; and, why any author would put themselves out there to be embarrassed and so wrong? It is the lie syndrome even many prostheticist suffer from.
Here's a few things some prostheticists (and so-called journalists) need to learn: Train staff to follow a few key rules. The first rule of platinum customer service is: "It's better to disappoint a customer with the truth, than to satisfy a customer with a lie." Telling the truth can be hard when it's something a customer does not want to hear, such as the brace or prosthesis won't be ready when promised. But remember that patients will judge you more harshly when they feel they are being misled. Learn to listen.
A big complaint among patients is that their doctor or the office staff did not listen to them about their medical issues or about some other matter such as a billing dispute. While today's more fast-paced world of health care does leave less time to listen, the good news is that any problems can be cured with a bit of practice.
And these two things above are just two of TEN things prostheticists need to do to adjust the amputee experience when they visit - and this was from the O & P Almanac of June 2010 Who do you think people will tend to believe? Someone who wears these knees - or someone who is dreaming and theorizing on paper - without a clue as to reality who is not even an amputee? "Beam me up Scotty" - there are no intelligent authors down here - they are all writing fiction like it is fact!!
There is no such thing as a bionic knee that mimics the human knee - and likely never will be - because they are not thought operated - they are swing operated. The only knee ever on the market was the Hydracadence knee that dorsi and plantar flexed the foot in the walk and swing cycle. . . that is another subject for another article. It is still made - but being the hydraulic king of the walking mimic process that it is - only certain people can appreciate it.